1,445 research outputs found
On 2-groups of almost maximal class
Let G be a 2-group of order 2^n, n>5, and nilpotency class n-2. The
invariants of such groups determined by their group algebras over the field of
two elements are given in the paper.Comment: 25 page
Fiber-optic realization of anisotropic depolarizing quantum channels
We employed an electrically-driven polarization controller to implement
anisotropic depolarizing quantum channels for the polarization state of single
photons. The channels were characterized by means of ancilla-assisted quantum
process tomography using polarization-entangled photons generated in the
process of spontaneous parametric down-conversion. The demonstrated
depolarization method offers good repeatability, low cost, and compatibility
with fiber-optic setups. It does not perturb the modal structure of single
photons, and therefore can be used to verify experimentally protocols for
managing decoherence effects based on multiphoton interference.Comment: 7 pages, 6 figure
Experimental characterization of three-wave mixing in a multimode nonlinear KTiOPO_4 waveguide
We report experimental determination of the phase-matching function for
type-II three-wave mixing in a periodically poled KTiOPO_4 waveguide in the
792-815 nm spectral region. The measurement was performed by sum-frequency
generation of spectrally tuned fundamental components. Strong dependence of the
observed signal on the excited spatial modes in the waveguide has been observed
and fully interpreted. These results indicate a route to employ the waveguide
for spontaneous parametric down-conversion producing photon pairs in
well-defined spatial modes.Comment: 4 pages, 4 figure
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